The present invention is generally related to operation of vehicles, such as locomotives, in the presence of faults in sensors used by the vehicle and, more particularly, the present invention is related a processor and method for accommodating failed speed sensors in the vehicle.
On vehicles propelled by traction motors, such as locomotives, transit vehicles, electric or hybrid buses, etc., each axle driven by one or more traction motors may have a respective speed sensor coupled thereto for providing control of the vehicle propulsion during various modes of operation of the vehicle, such as during motoring and braking. Typically, in a locomotive, the speed sensors may also be used for providing various operational functions, such as locked-axle detection, torque production, slow speed control, speedometer, cab signaling equipment, event recorder, etc. It will be appreciated that some of these functions, such as locked-axle detection may require speed sensor information from each axle. For other functions, speed sensor information from one axle or some times from two axles may be sufficient.
One known implementation, as shown in FIG. 1, allows for selecting speed sensor information from one predefined single axle, e.g., axle two, and using this speed sensor information for controlling functions like speedometer, event recorder, cab signaling, etc. By way of example, two such functions that require speed sensor information, Function 1 and Function 2, are represented in FIG. 1. One of such functions, Function 1, uses information from one speed sensor and the other function, Function 2, e.g., a function potentially affecting safety issues, may use inputs from multiple sensors, e.g., two or more distinct speed sensor inputs. As shown in FIG. 1, the same speed sensor input may be used for multiple functions, however, in the implementation of FIG. 1 there are speed sensors which are not used, e.g., speed sensors 1, 3, 4 and 6. Thus, in this example, a fault of a single speed sensor, e.g., speed sensor 2, could disable Functions 1 and 2.
When speed sensors on any axle fail, functions like torque production and locked-axle detection could be performed using other information, that is, information other than speed sensor information, especially on AC locomotives. Thus, respective known techniques may allow for providing torque production, or locked axle detection, or both, without speed sensor information. However, when speed sensor information from the predefined single axle is faulty, respective functions, such as those represented in FIG. 1, that do not rely on speed sensor information from other axles, like speedometer, event recorder, cab signaling, etc., would also fail. This type of failure may be costly and time consuming since it causes locomotives to be inoperative.
Thus, there is a need for avoiding the foregoing drawbacks so that the locomotive may continue to operate even when some of the speed sensors fail, at least until the failed speed sensor may be repaired and/or replaced at an appropriate service shop.
Generally speaking, one aspect of the present invention fulfills the foregoing needs by providing in one exemplary embodiment thereof a method for accommodating failed speed sensor in a locomotive. The method allows for providing predefined operational functions in the locomotive. The functions may be based on one or more speed sensor signals from a plurality of speed sensors in the locomotive. The method further allows for continuing to provide the operational functions even in the presence of faults in some of the speed sensors.
In another aspect thereof, the present invention further fulfills the foregoing needs by providing a computer-readable medium encoded with computer program code for accommodating failed speed sensors in a locomotive. The program code causes a computer to execute a method that allows for providing predefined operational functions in the locomotive. The functions may be based on one or more speed sensor signals from a plurality of speed sensors in the locomotive. The method further allows for continuing to provide the operational functions even in the presence of faults in some of the speed sensors, and for monitoring the respective health status of the plurality of speed sensors.
In yet another aspect of the present invention, the foregoing needs may be fulfilled by providing a processor configured to accommodate failed speed sensors in a locomotive so that predefined operational functions in the locomotive, based on one or more speed sensor signals from a plurality of speed sensors, continue uninterrupted even in the presence of faults in some of the speed sensors. The processor comprises a monitor module configured to monitor the respective health status of the plurality of speed sensors, and a control signal generator configured to generate a control signal based on the monitored speed sensor health status.